Salvaging a seat belt bolt

[Crossthreaded]

I had the front seat belts restored and in the process of reinstalling the PS belt have had trouble reinstalling the bottom bolt that holds the retractor. The bottom 3-4mm are quite stripped. From older threads I take it this is a unique Toyota 11mm bolt with a 14mm hex head and a 13-14mm shoulder that is not available. To replace the OEM bolt means buying an entire seat belt assembly. Measuring the threads I get a better fit with an M12x1.5 than the standard 7/16x20 used for seat belts. What would you do?

 

[CharlieS]

If you don't have the tools to clean the threads, buy a good used one from one of the guys on here that parts out land cruisers, or get a new one from a dealer parts department or online equivalent.

 

[PIP]

Grind the bad leading threads off. Then either grind a 1/16" wide slot into one side of the bolt, deeper than the threads or grind a single notch through the first 4-5 threads on the end to form a cutting flute like a tap has.

The slot or notch will accomplish the same thing. The bolt will start and will clean out the old threads as it goes in instead of jamming up. Use some oil or grease on the bolt threads when you install them.

Even if you get a replacement bolt I recommend doing these mods to the old bolt and threading it in to clear the old threads first. Or buy the correct tap to chase the threads with.

 

[LandCruisinMy93]

I had the front seat belts restored and in the process of reinstalling the PS belt have had trouble reinstalling the bottom bolt that holds the retractor. The bottom 3-4mm are quite stripped. From older threads I take it this is a unique Toyota 11mm bolt with a 14mm hex head and a 13-14mm shoulder that is not available. To replace the OEM bolt means buying an entire seat belt assembly. Measuring the threads I get a better fit with an M12x1.5 than the standard 7/16x20 used for seat belts. What would you do?

View attachment 3630195

are you sure that is an M11? I have never in my many years as a mechanic or enthusiast dealt with an M11, especially in a Toyota.

 

[mudgudgeon]

Agree with PIP, use a spare bolt to make a cleaning tap. Super easy, and effective.

Seat beat bolts are/were all 7/16 under international standardisation.

Go to a pick and pull and find a bolt to match yours with same shoulder.
Grab a spare with good threads to cut your cleaning tap from

 

[thatcabledude]

Username certainly checks out.

 

[PIP]

are you sure that is an M11? I have never in my many years as a mechanic or enthusiast dealt with an M11, especially in a Toyota.

M11 is actually pretty common in automotive.

Toyota uses M11 in driveline mating flanges.

GM uses M11 extensively for head bolts in LS, Northstar and Atlas engine platforms.

 

[LandCruisinMy93]

M11 is actually pretty common in automotive.

Toyota uses M11 in driveline mating flanges.

GM uses M11 extensively for head bolts in LS, Northstar and Atlas engine platforms.

not saying it doesn't happen. But I've never seen it. Seen plenty of m10x1.0 and M10x1.5 for Toyota driveline bolts but I can't recall any M11. In over 20 years of working on stuff I can't recall ever running into anything that strange. Maybe a M7x1.0 which is fairly common on Euro stuff. I literally have boxes of hardware from Toyotas, hondas, Nissans, some rando Dodge, mercedes, VW/Audi etc... most of it falls into a narrow spectrum of Even numbe sizes. M5 and M7 are the only Odd numbered sizes I have.

I'm going with @mudgudgeon on the 7/16 unf. If you have calipers and the outer diameter is greater than or very very close to 11mm its likely 7/16 as most metric bolts are a few tenths undersize.

 

[mudgudgeon]

Pretty sure 1fz-fe head and main bearing cap bolts are M11. Not really relevant though

There's something things automotive that are or were covered by ISO standards. Seat belt bolts was one. I think brake line pipe and fittings was another.

I think that may have changed somewhat. The seat belt bolts I pulled from Audi seats were metric. Bolts in the floor pan were still 7/16

 

[PIP]

not saying it doesn't happen. But I've never seen it. Seen plenty of m10x1.0 and M10x1.5 for Toyota driveline bolts but I can't recall any M11. In over 20 years of working on stuff I can't recall ever running into anything that strange. Maybe a M7x1.0 which is fairly common on Euro stuff. I literally have boxes of hardware from Toyotas, hondas, Nissans, some rando Dodge, mercedes, VW/Audi etc... most of it falls into a narrow spectrum of Even numbe sizes. M5 and M7 are the only Odd numbered sizes I have.

I'm going with @mudgudgeon on the 7/16 unf

Sure, they probably are 7/16".

The rear driveline bolts in your 80 series are M11x1. GM uses M11x2 A LOT.

 

[LandCruisinMy93]

Sure, they probably are 7/16".

The rear driveline bolts in your 80 series are M11x1. GM uses M11x2 A LOT.

Interesting. You learn something new every day. I have spares somewhere I will have to check that out when I get home. If they're m11 I've never paid them any mind. I've had them on and off a number of times and they never caught my attention.

As far as GM, wouldn't know. Never had to find new hardware for them. All the drive train work I've done on GM and Dodge was usually warranty work or remans from Jaspers. They only Chevy engines I rebuilt were for personal rigs and were from the late 70s.

 

[DIRTBIKEUSA]

A thread file will clean that right up.

 

[JoeCova]

I had the front seat belts restored and in the process of reinstalling the PS belt have had trouble reinstalling the bottom bolt that holds the retractor. The bottom 3-4mm are quite stripped. From older threads I take it this is a unique Toyota 11mm bolt with a 14mm hex head and a 13-14mm shoulder that is not available. To replace the OEM bolt means buying an entire seat belt assembly. Measuring the threads I get a better fit with an M12x1.5 than the standard 7/16x20 used for seat belts. What would you do?

View attachment 3630195

If I recall these are not metric, specifically a NHTSB thing so they are SAE. I used a grade 8 SAE with lock washer.

 

[Crossthreaded]

Grind the bad leading threads off. Then either grind a 1/16" wide slot into one side of the bolt, deeper than the threads or grind a single notch through the first 4-5 threads on the end to form a cutting flute like a tap has.

The slot or notch will accomplish the same thing. The bolt will start and will clean out the old threads as it goes in instead of jamming up. Use some oil or grease on the bolt threads when you install them.

Even if you get a replacement bolt I recommend doing these mods to the old bolt and threading it in to clear the old threads first. Or buy the correct tap to chase the threads with.

Thanks PIP - this worked really well. Glad to see the end of this particular project. Thanks also to everyone who responded. The attachment points to either side of the hatch in the back are 7/16 and I assume those were for the 3rd row harnesses? If so it's mix and match as the fronts are definitely 11mm. 7/16 may have worked but it was wobbly when I tried it with a bolt thread checker.

And though I wasn't the one to strip this particular bolt, the username has some validity. Working my way up to mediocre mechanic to match my motorcycle wrenching skills.